Gas-filled body

ABSTRACT

The invention concerns a plastic tube ( 1 ) which is prefabricated for the production of gas-filled filling bodies. The plastic tube ( 1 ) comprises an upper film and a lower film which are in mutually superposed relationship and which are connected together along their two longitudinal edges ( 4, 6 ). In that case provided in the upper film is a transverse cut ( 12 ) which is preferably cut in at its ends by stampings ( 10 ). In addition the upper film and the lower film are subdivided into individual pockets ( 7 ) by weld seams extending in the transverse direction and spaced from each other. The plastic tube can be easily filled by injecting a filling gas, wherein after inflation of the pockets ( 7 ) the open ends thereof are welded.

The invention concerns a prefabricated plastic tube for the productionof gas-filled filling bodies, comprising an upper film and a lower filmwhich are gas-tightly connected together in mutually superposedrelationship at a first of their longitudinal edges and which are weldedtogether to form inflatable pockets in a transverse direction bygas-tight weld seams arranged at a spacing relative to each other. Theinvention further concerns a gas-filled filling body for the packagingof articles, a process for the production of said plastic tube and of agas-filled filling body, and an apparatus for carrying out thelast-mentioned process.

Gas-filled filling bodies are used for example for cushioning articlesin transportation cases in order thereby to prevent the articles beingtransported from being subjected to vibration or suffering damage. Thefilling bodies are first filled with gas immediately prior to usethereof and therefore can be delivered to and stored at the packager orconsumer in a configuration such as to save on a great deal of space. Afurther advantage of the filling bodies is that, by virtue of their lowweight, they scarcely increase the packaging weight and after usethereof they can be recycled without being separated into theirrespective constituents as they are usually made from a single plasticmaterial.

In this respect, DE 199 13 408 A1 discloses a prefabricated plastic tubeof the kind indicated in the opening part of this specification, inwhich the upper film and the lower film are welded together to forminflatable pockets in the transverse direction by mutually spaced pairsof gas-tight weld seams, wherein the weld seams extend from the firstlongitudinal edge to a predetermined distance from the oppositelydisposed second longitudinal edge. The pockets each have a gas fillingopening between the upper and lower films, which is accessible from thesecond longitudinal edge. As a full plastic tube is generally theinitial starting point for the production of such a plastic tube, itfirstly has to be divided in the longitudinal direction into twohalf-tube portions which are open at one side. That requires anadditional working step before the actual operation for prefabricationof the plastic tube can be effected. A further problem with the knownplastic tube is that the shrinkage which inevitably occurs with thewelding of plastic films has the result that the film runs out of itsoriginal direction of transportation movement.

With that background in mind, the object of the present invention was toprovide a prefabricated plastic tube and a process and an apparatus forthe simpler production of filling bodies.

That object is attained by a plastic tube having the features of claim1; by a gas-filled filling body having the features of claim 7, by aproduction process having the features of claim 8, by a process havingthe features of claim 11 and by an apparatus having the features ofclaim 14.

Advantageous configurations are set forth in the appendant claims.

The plastic tube which is prefabricated for the production of gas-filledfilling bodies has two films which are referred to as the upper film andthe lower film and which are arranged in mutually superposedrelationship and which are gas-tightly connected together at a first oneof their longitudinal edges. The upper film and the lower film are alsowelded together to form inflatable pockets in the transverse directionby mutually spaced gas-tight weld seams. The plastic tube ischaracterised in that the films are also connected together continuouslyat their second longitudinal edge and that one of the films which isdefined hereinafter by definition as the upper film has a transverse cutin the transverse direction.

Unlike the known prefabricated plastic tubes the described plastic tubeis closed at both longitudinal edges and has a transverse cut. Thatdifference has on the one hand advantages in regard to manufacturingprocedure as the initial starting point adopted is not a half-tubeportion which firstly has to be cut out of a full tube in a separateworking operation. Rather, it is possible directly to use a full tube(in a condition of being laid flat) so that an entire film tube can befilled in one working operation. The output of a correspondingmanufacturing installation can thus be virtually doubled as there is noneed for two half-tube portions to be filled in succession. In additionthe transverse cut which is disposed in the transverse direction meansthat the weld seams to be applied for closing the pockets afterinflation thereof also extend in the transverse direction. That isadvantageous over a welding operation at a longitudinal edge as in thecase of the known film as such welding and introduction of the air at alongitudinal edge of the film necessarily results in an asymmetry, byvirtue of which the film can at one side run out of its previousdirection of movement. In contrast such an asymmetry is avoided when atransverse cut is involved. The transverse cuts are preferably arrangedsymmetrically with respect to the center line of the plastic tube inorder to exclude any ‘preferment’ of one side of the plastic tube, whichcould result in asymmetry.

In accordance with a preferred configuration of the plastic tube theweld seams which extend in the transverse direction are provided inpairs, wherein an intermediate space is provided between the two weldseams of each pair thereof, a perforation through the two filmsextending in the intermediate space in the transverse direction.Preferably the perforation extends continuously from one longitudinaledge of the plastic tube to the other. After the inflatable pockets havebeen filled and after they have been gas-tightly welded, the perforationpermits the filling bodies produced in that way to be separated fromeach other by being torn away.

In accordance with another possible configuration of the plastic tubethe transverse cut ends at at least one side but preferably at both at acertain spacing relative to the longitudinal edge of the plastic tube,wherein moreover a (short) incision in the longitudinal direction isdisposed at said end. Such an incision which is perpendicular to thetransverse cut interrupts the direction of run of the transverse cut andthereby prevents the upper film from being further unintentionally tornin the transverse direction. In addition the incisions have theadvantage that the edge of the upper film, which is delimited by thetransverse cut, thereby forms a freely movable flap which can be pivotedopen or up when introducing the gas.

In accordance with another development of the plastic tube it has weldseams which are arranged in pairs and which extend in the longitudinaldirection and between which is arranged a perforation also extending inthe longitudinal direction. Pairs of weld seams of that kind with aninterposed perforation also subdivide the plastic tube in thelongitudinal direction into (at least) two portions so thatcorrespondingly narrower inflatable pockets are formed. The narrowerfilling bodies formed therefrom permit a greater degree of flexibilityin regard to their use as packaging material, wherein heightwisedistribution of the filling bodies is overall more uniform than in thecase of wider filling bodies.

As has already been explained hereinbefore the double-sided connectionof the longitudinal edges of the plastic tube can be achieved by using afull tube in a laid-flat condition as the starting material. In order toincrease the stability, which is reduced by the transverse cut, of theplastic tube for transport purposes or in order to allow smallerthicknesses for the plastic films with the same level of stability, apreferred embodiment of the invention provides that the longitudinaledges of the plastic tube are connected together by weld seams in thelongitudinal direction.

The weld seams extending in the longitudinal direction (at thelongitudinal edges or centrally in pairs) can be of a continuousconfiguration. Preferably however they are interrupted at the rhythm ofthe transversely extending weld seams, wherein their portions arerespectively disposed with their first end on a first transverselyextending weld seam and end with their second end at a certain spacingrelative to the next transversely extending weld seam. The transversecut also extends between the second end and the spaced next transverselyextending weld seam. Such an arrangement is particularly advantageouswhen the upper film and the lower film are separate in themselves andare only connected by the weld seams at the longitudinal edges. Morespecifically, in that case the interruptions in the weld seams extendingin the longitudinal direction give rise to transverse strips in whichthe upper and lower films are unconnected over their entire width. Acutting apparatus can then be particularly easily introduced into thosetransverse strips in order to produce the transverse cut through theupper film. In that respect, a flap which can be freely pivoted open atits edges is advantageously formed.

In addition the plastic strip may have markings which form codings forindicating the position of the weld seams and/or for indicating the filmthickness and/or for indicating the film width. Markings for indicatingthe position of the weld seams eliminate expensive synchronisation,which would otherwise be required, for the apparatus for the productionof filling bodies. The markings are preferably in the form ofstamped-out openings but they could also be printed on, in an equallypreferred fashion. In addition markings with items of coded informationabout the nature of the plastic tubes can be printed on or stamped out.In that way an apparatus for filling the plastic tubes according to theinvention can detect the nature of the film just being introduced intothe apparatus (for example film thickness, material, dimensions) andthus automatically adapt various operating parameters such as forexample the welding time and temperature, the filling amount or fillingtime, the speed of transportation movement, and transportation distancesand so forth.

The markings are preferably arranged on a line with the perforations oralso in the immediate proximity thereof and are preferably stamped outin production of the tube by the same tool which also forms theperforations so that there is no need for an additional workingoperation.

In addition (preferably in the region of the transversely extendingperforations and at least in the proximity of the longitudinal edges),there can be stamped-out openings for the engagement therein of a barfor further transportation of the tube. In that way the plastic tube canbe easily passed through an apparatus.

The invention further concerns a gas-filled filling body for thepackaging of articles, which is characterised in that it has beenproduced from a plastic tube of the kind discussed hereinbefore.Preferably a gas-filled filling body of that kind can contain an articleto be packaged (individual article or solid/fluid filling material orloose bulk material) together with a defined amount of air. An articlewhich is enclosed in the filling body in that way is optimally protectedfrom shocks and vibration. The article can be removed at any time againwhen required by cutting the filling body. Disposing an article in thefilling body is to be particularly well implemented when using theplastic tube according to the invention as it has a wide transverse cut,by way of which the article can be introduced.

The amount of air which is additionally enclosed in the filling bodywith the article to be packaged can be adapted to the respectivepackaging task involved. If completely inflated filling bodies are notwanted, then, after introduction of the articles and shortly before thewelding operation, a predetermined part of the injected air can be urgedout again by a stripping device. Subsequently allowing air to bedischarged in that way affords the advantage that the operation ofintroducing the articles into the completely inflated filling bodiestakes place particularly easily, with the volume of the finished fillingbodies being reduced in relation thereto. The article is protectedduring transportation by the surrounding air. The air cushions which areformed in that way and which are filled with an article can beintroduced for example in the form of a continuous web in a meanderconfiguration into a cardboard box.

The invention further concerns a process for the production of a plastictube of the above-discussed kind, wherein

-   -   a double layer is formed from an upper film and a lower film,        which can be effected in particular by laying a full tube flat;    -   the weld seams extending in the transverse direction which        delimit the individual inflatable pockets are produced;    -   at least one through hole is stamped through the upper film and        the lower film; and    -   a cutting tool is introduced into said hole into the space        between the upper film and the lower film and the upper film is        thereby cut in the transverse direction to produce the        transverse cut in the plastic tube.

The above-outlined process makes it easily possible for the desiredtransverse cut through the upper film to be produced. Preferably theindividual steps of the process are executed in the specified sequence,but in that respect it is also possible in particular for the operationof producing the weld seams in the transverse direction to be effectedafter the stamping operation or production of the transverse cut.

In an alternative process for the production of a plastic tube accordingto the invention which is advantageously combined with theabove-specified process the following steps are carried out:

-   -   a double layer comprising an upper film and a lower film        separate therefrom is formed, wherein the upper film and the        lower film can be produced for example by cutting a full tube at        two sides in the longitudinal direction. Preferably in that case        one of the films (for example the upper film) is narrower in        dimension than the other film (lower film) so that the wider        film projects somewhat at both longitudinal edges of the plastic        tube and can thus be engaged separately at those edges for        transportation purposes;    -   the upper film and the lower film are welded together by weld        seams extending in the longitudinal direction in the region of        the longitudinal edges.

The connection of the longitudinal edges by way of weld seams has theadvantage that they lead to stabilisation of the resulting plastic tubeand thus counteract the destabilising effect of the transverse cut.

In accordance with a development of the last-mentioned process the weldseams extending in the longitudinal direction are so effected that theyhave interruptions, wherein the upper film is cut at the location ofthose interruptions in the transverse direction to produce thetransverse cuts. That interrupted configuration of the weld seamsextending in the longitudinal direction has the advantage of affordingtransverse strips in which the upper film and the lower film areunconnected. A tool for cutting open the upper film can be particularlyeasily introduced into those transverse strips, while in addition a flapwhich is free at the edges is afforded by the transverse cut.

The invention further concerns a process for the production ofgas-filled filling bodies comprising the following steps:

-   -   a) providing a prefabricated plastic tube of the kind described        hereinbefore;    -   b) injecting air or another filling gas into each pocket through        the gas filling opening which is formed by the transverse cut in        the upper film of the plastic tube, and    -   c) gas-tight welding of the gas filling opening of the        gas-filled pockets.

The specific configuration of the plastic tube used means that such aprocess can be very advantageously carried into effect. In particularthe symmetrical effect of inflation and welding means that the plasticfilm no longer has a tendency to run out of its direction oftransportation movement.

In the foregoing process the plastic tube, in the second processing stepb), in injection of the filling gas, is preferably guided in a bendwhich faces away from the upper film and which typically can be 90°.Such a bend configuration causes the flaps formed by the transverse cutto flap open so that the filling opening is ‘automatically’ accessiblefor the operation of injecting the filling gas.

In accordance with a further development of the process prior to thewelding operation in step c) an article to be packaged is introducedinto the pocket which is to be inflated or which is already inflated.The subsequent welding operation provides that that article is enclosedin the pocket and thereby afforded optimum protection.

The invention further concerns an apparatus for carrying out theabove-depicted process, characterised by the following components:

-   -   a holder for a supply of tube;    -   a transport device for transporting the tube through the        apparatus;    -   a gas filling device having a nozzle with which air or another        filling gas can be injected into the gas filling openings of the        pockets; and    -   a welding device having a welding tool with which the gas        filling openings of the pockets are gas-tightly closable with a        weld seam extending in the transverse direction of the tube,    -   wherein at the gas filling device the transport device is of a        configuration which bends away from the upper film.

In order to minimise possible leakage of filling gas the gas fillingdevice may preferably have hold-down means which, during theintroduction of the gas, press the flap of the upper film, which isformed by the transverse cut, against the gas filling device.

The apparatus may also have detection means for markings on the plastictube, by which the machine speed and/or the gas filling amount and/orthe welding time can be controlled. It is thus possible, by means ofsuch devices, to fill plastic tubes prefabricated in different ways, inthe apparatus, in which respect it can be automatically adapted to therespective optimum conditions.

The transport device of the apparatus can cyclically transport theplastic tube. In other words, the filling operation and the weldingprocedure each take place when the tube is stationary and the tube isthen further transported by a pocket length.

It is particularly preferable nevertheless if the plastic tube iscontinuously moved past the gas filling device and the welding device.Such a mode of operation generally allows a greater production output,while the complication and expenditure in respect of control systems canbe kept lower by possibly eliminating the cyclic control.

The invention is described in greater detail hereinafter by way ofexample with reference to the Figures in which:

FIG. 1 shows a cross-section through the plastic tube of FIG. 2 takenalong line I-I,

FIG. 2 is a plan view of a first embodiment of a plastic tube accordingto the invention which is produced from a laid-flat full tube,

FIG. 3 is a longitudinal section through the plastic tube of FIG. 2taken along line III-III,

FIG. 4 shows a view on to the plastic tube of FIG. 2 after welding ofthe inflated pockets,

FIG. 5 shows a cross-section through the plastic tube of FIG. 4 takenalong line V-V, showing a pocket which has just been inflated as well asan inflated and welded pocket,

FIG. 6 shows a view on to and a cross-section and a longitudinal sectionof a second embodiment of a plastic tube with welded longitudinal edges,and

FIG. 7 shows a view on to and a cross-section and a longitudinal sectionof a third embodiment of a plastic tube with welds interrupted inpocket-wise manner at the longitudinal edges and in the central region.

FIGS. 1 through 5 show a first embodiment of a plastic tube 1 accordingto the invention, which is prefabricated for easier manufacture ofgas-filled filling bodies for packaging purposes. The plastic tube 1 isproduced starting from a laid-flat full tube, having an upper film 2 anda lower film 3 which are connected together at their two longitudinaledges 4 and 6.

In the transverse direction the plastic tube is subdivided by pairs ofweld seams 5 consisting of a first weld seam 5 a and a second weld seam5 b into inflatable pockets 7. Disposed between the weld seams 5 a, 5 bof a pair 5 thereof is a perforation 9 which extends transversely fromthe longitudinal edge 4 to the longitudinal edge 6 and along which theindividual pockets 7 or later the gas-filled filling bodies 7′ can beseparated from each other by being torn apart.

The prefabricated plastic tube 1 also has a transverse cut 12 extendingin the transverse direction, through the upper film 2. That transversecut 12 forms a filling opening 8 (FIG. 3), by way of which a filling gascan be injected into the pocket 7 between the upper film and the lowerfilm. The transverse cut is preferably already present in theprefabricated film but it may also only be formed therein in the courseof filling by a filling apparatus.

Provided at the two ends of the transverse cut 12 are preferably shortincisions 10 extending in the longitudinal direction, thereby affordinga flap 11 which can be pivoted open.

The operation of producing the transverse cuts 12 is preferably effectedin such a way that firstly holes 10 are stamped through the upper filmand the lower film, and then a cutting tool can be introduced throughthe holes 10 for cutting the upper film in the transverse direction.

FIGS. 4 and 5 show the plastic tube 1 during the operation of fillingthe pockets 7 with a filling gas which is injected into the pockets 7through the filling opening 8. In this case, unlike the situation shownin FIG. 5, the plastic tube 1 can advantageously be diverted by way of abend of for example 90° so that the detached flap 11 flaps open of itsown accord by virtue of retaining its direction.

FIG. 5 also indicates that, besides the filling gas, an article 15 to bepackaged (individual article or loose material) can also be introducedinto the filling body, whereby it is packaged in such a way as to enjoyoptimum protection. The operation of introducing the article ispreferably effected at the moment at which the plastic tube 1 isdeflected through a 90° bend so that the article can be ‘thrown’ intothe pocket which is formed in that way, due to the effect of the forceof gravity. Subsequently or at the same time the pocket is filled with adefined volume of air and then welded. In that way the articles—forexample filigree glass pieces—are protected by an air cushion, in whichcase the web of air cushions issuing from the machine can be transportedwithout any problem and can later be subjected to further processing bymachine; in other words, the film web can be later cut open in amachine, in which case the articles can be individually removed.Alternatively, in the situation where a smaller volume is wanted for theair cushion pockets, it is also conceivable that, after the articleshave been introduced into the pockets and prior to the weldingoperation, a part of the air can be removed from the pockets in order inthat way to afford a smaller transportation volume.

FIG. 4 shows the weld seams 13 which extend in the transverse directionand which are produced after the injection of the filling gas. That canbe effected for example in a suitable apparatus by a kind of flap with aheating wire dropping down and welding the upper film to the lower film.In that case (looking at FIG. 4) the weld seams 13 must be disposedbelow the longitudinal cuts 12 and the holes 10 which are stamped outfor that purpose, in order to close off a corresponding pocket spacegas-tightly therearound.

The gas-filled and completely sealed, finished filling bodies 7′ canthen be separated from each other along the transversely extendingperforations 9.

In the alternative embodiment of a plastic tube as shown in FIG. 6, incontrast to that shown in FIGS. 1 through 5, the two longitudinal edgesare connected to each other (additionally or exclusively) by weld seams14 and 16 respectively. Weld seams of that kind in the longitudinaldirection contribute to stabilisation of the plastic tube and thuscounteract the slightly destabilising effect of the transverse cuts.

FIG. 7 shows a modification of the embodiment of FIG. 6. In this casethe upper film 2 and the lower film 3 are again connected by weld seams24 and 26 respectively which extend in the longitudinal direction, butin this case they are not continuous but each only extend from a firsttransversely extending weld seam 5 b as far as a spacing from the nexttransversely extending weld seam 5 a. In that case, the transverse cut12 through the upper film 2 is between the last-mentioned weld seam 5 aand the end of the weld seams 24 and 26.

In addition in the embodiment shown in FIG. 7 the lower film 3 issomewhat wider than the upper film 2 so that it projects somewhat atboth sides at the longitudinal edges 4 and 6 respectively. The lowerfilm 3 can be engaged and guided at those projecting portions, by asuitable apparatus.

It can also be seen from FIG. 7 that arranged at the center of theplastic tube 1 are further weld seams 21 and 22 which extend in parallelrelationship in the longitudinal direction and between which is provideda perforation 20 which is continuous in the longitudinal direction. Thatdivides the plastic tube into two in the longitudinal direction, so thatrespective mutually juxtaposed inflatable pockets 7 a, 7 b are formed.

1. A plastic tube (1) for the production of gas-filled filling bodiescomprising: an upper film (2) and a lower film (3) said upper film andsaid lower film being gas-tightly connected together in mutuallysuperposed relationship at a first respective longitudinal edge (4) andbeing welded together to form inflatable pockets (7, 7 a, 7 b) in thetransverse direction by gas-tight weld seams (5 a, 5 b) arranged at aspacing relative to each other, said upper film and said lower film (2,3) being connected together continuously at a second respectivelongitudinal edge (6) and said upper film (2) having a transverse cut(12) in the transverse direction.
 2. A plastic tube as set forth inclaim 1 wherein said weld seams extending in the transverse directionare arranged in pairs, wherein provided between said weld seams (5 a, 5b) of each pair (5) thereof is an intermediate space in which aperforation (9) through both films extends in the transverse direction.3. A plastic tube as set forth in claim 1 wherein said transverse cut(12) ends at a spacing relative to the longitudinal edges (4, 6) andthat incisions (10) are arranged at its ends in the longitudinaldirection.
 4. A plastic tube as set forth in claim 1 wherein weld seams(21, 22) are provided extending in the longitudinal direction and saidweld seams (21, 22) are arranged in pairs and between said pairs isprovided a perforation (20) extending in the longitudinal direction. 5.A plastic tube as set forth in claim 1 includes longitudinal edgesconnected by weld seams (14, 16, 24, 26).
 6. A plastic tube as set forthin claim 5 wherein said weld seams (21, 22, 24, 26) extending in thelongitudinal direction comprise portions having a first end respectivelydisposed on a first transversely extending weld seam (5 b) and a secondend is at a spacing relative to a next transversely extending weld seam(5 a), wherein said transverse cut (12) extends through the upper filmbetween said second end and said next weld seam (5 a).
 7. A plastic tubeas recited in claim 1 includes a gas-filled filling body (7′) containingan article (15) to be packaged.
 8. A process for the production of aplastic tube comprising the steps of: forming a double layer from anupper film (2) and a lower film (3); producing weld seams (5 a, 5 b) inthe transverse direction; stamping at least one hole (10) through theupper film (2) and the lower film (3); and providing a cutting tool intosaid at least one hole and cutting said upper film (2) in the transversedirection to produce a transverse cut (12).
 9. A process for theproduction of a plastic tube as set forth in claim 8, wherein the stepof forming a double layer includes the steps of providing one of saidupper films (2) narrower than said other lower film (3); and weldingsaid upper film (2) and said lower film (3) together by weld seams (14,16, 24, 26) extending in the longitudinal direction.
 10. A process asset forth in claim 9 includes providing interruptions in said weld seams(24, 26) extending in the longitudinal direction at the level of whichthe upper film (2) is cut in the transverse direction to produce thetransverse cuts (12).
 11. A process for the production of gas-filledfilling bodies (7′) comprising the steps: a) providing a prefabricatedplastic tube (1) having an upper film (2) and a lower film (3); saidupper film and said lower film being gas-tightly connected together inmutually superposed relationship at a respective first longitudinal edge(4) and welded together to form inflatable pockets (7, 7 a, 7 b) in atransverse direction by gas-tight weld seams (5 a, 5 b) arranged at aspacing realive to each other; said upper film and said lower film beingconnected together continuously at a second respective longitudinal edge(6) and said upper film (2) having a transverse cut (12) in thetransverse direction; b) injecting air or another filling gas into eachsaid inflatable pocket (7, 7 a, 7 b) through a gas filling opening (8)formed by said transverse cut (12) in said upper film (2) of the plastictube (1), and c) gas-tight welding of the gas filling opening (8) of thegas-filled pockets (7).
 12. A process as set forth in claim 11 whereinthe injecting step includes the step of guiding the air or anotherfilling gas into a bend facing away from the upper film (2).
 13. Aprocess as set forth in claim 11 includes the step, prior to the weldingoperation in step c) introducing an article to be packaged (15) into onesaid pocket (7).
 14. An apparatus for carrying out a process for theproduction of gas-filled filling bodies (7′) comprising: a holder for asupply of tube; a transport device for transporting the tube through theapparatus; a gas filling device having a nozzle for injecting air oranother filling gas into a gas filling openings (8) of a plurality ofpockets (7, 7 a, 7 b); and a welding device having a welding tool forwelding said gas filling openings (8) of said pockets (7, 7 a, 7 b)gas-tightly closable with a weld seam (13) extending in a transversedirection of the tube, wherein at said gas filling device, saidtransport device bends away from the upper film.